Parking brake not applied warning whilst driving ?

I have a automatic DAF LF45 63 reg which keeps bringing up a warning light saying my parking brake not applied but this is while I am driving. Doors are shut so it shouldn’t be coming on. I’ve had the relays replaced in March and the passenger door sensors. It’s ran ok then tonight it came on again. When I stopped I turned the engine off but the dash all lit up as if I’d turned the ignition when I opened my door but turned off again when shut.
Has anyone else had a similar problem and a resolution to the problem?